Objective To study the seasonal distribution characteristics of polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 in Lianyungang City, and analyze the sources of PAHs pollution, and to evaluate the health risks of PAHs in different seasons. Methods PM2.5 samples were collected regularly from January 2019 to December 2023, and 16 types of PAHs were determined by HPLC. Kruskal-Wallis H test was used to compare the concentrations of PM2.5 and PAHs in different years and seasons. The source of PAHs was analyzed by characteristic ratio and principal component analysis (PCA). Health risks were assessed using the BaP equivalent method and the incremental lifetime cancer risk (ILCR) model. Results The annual exceedance rates of PM_2.5 and BaP in Lianyungang showed a decreasing trend from 2019 to 2023. PM_2.5, total PAHs and PAHs monomers (except Ace, Flu and Acy) all showed significant seasonal differences, with the highest concentration in winter (P<0.001). The average proportion of 4-ring PAHs was the highest and the average proportion of 2-ring PAHs was the lowest. The proportion of 5-6 ring PAHs was relatively high in winter and spring. PM2.5and PAHs were negatively correlated with temperature, relative humidity and precipitation, and were positively correlated with atmospheric pressure. PM_2.5 was negatively correlated with wind speed, while some PAHs monomers were positively correlated with wind speed. The characteristic ratio and PCA results showed that the main sources of PAHs in Lianyungang City were mixed sources of road dust and vehicle emissions, oil pollution sources and biomass combustion sources. The results of ILCR showed that the highest risk was found in adults, with males slightly higher than females. In Lianyungang, the maximum value of ILCR in winter was more than 10-6 in people over 9 years old. Conclusion The main sources of PAHs in PM_2.5 in Lianyungang City are mixed sources of road dust and vehicle emissions, oil pollution sources, and biomass combustion sources. Under the current exposure level of PAHs in PM_2.5, residents have a certain potential carcinogenic risk.